1. Field of Invention
This application relates to a tracking device, having one controllable degree of freedom, that is movable with six degrees of freedom.
2. Description of Related Art
Tracking devices may be used in areas such as planetary exploration, mobile remote sensing, tracking of moving land-based agents such as people, animals, and automobiles, automatically deployable parameter sensors, and smart bombs. However, in order for the tracking device to move with six degrees of freedom, complicated propulsion and control systems are necessary. This results in tracking devices of increased cost and size.
Eukaryotic single-celled micro-organisms function as tracking devices but are capable of controlling only one degree of freedom. The micro-organisms are capable of movement with six degrees of freedom, however, toward and away from a sensed stimuli, such as food sources and light. The micro-organisms control their one degree of freedom to essentially move forward in a helical pattern. The micro-organisms track a stimuli by modulating the speed of their one degree of freedom motion through a simple feedback system. As the micro-organism spins around, it senses the stimuli sinusoidally. By modulating its spinning speed in a manner directly proportional to the sensed stimuli, the micro-organism moves toward, or away from, depending on the sense of modulation, the stimuli by precession, i.e., the motion of an axis of the microorganism due to an applied external force. The motion of single-celled microorganisms is described more thoroughly in xe2x80x9cOrientation by Helical Motionxe2x80x94I. Kinematics of the Helical Motion of Organisms with up to Six Degrees of Freedom,xe2x80x9d by Hugh C. Crenshaw, published in the Bulletin of Mathematical Biology, Vol. 55, No. 1, pp. 197-212 (1993).
Self-propelled balls used as toys and amusement devices are known, for example, from U.S. Pat. Nos. 5,533,920, 5,439,408, and 4,438,588. U.S. Pat. No. 5,533,920 to Arad et al. discloses a self-propelled musical toy ball having a centrally or eccentrically mounted self-propelling device and an integrated circuit sound effects chip. The ball includes a bump switch that causes the self-propelling device to turn off if the ball runs into an obstacle. U.S. Pat. No. 5,439,408 to Wilkinson discloses a remote control movable ball amusement device that has a propulsion mechanism including a receiver and a drive unit. The drive unit includes eccentrically mounted weights rotated by a motor that is activated by a signal from a remote control unit. U.S. Pat. No. 4,438,588 to Martin discloses a remote control ball including a remote control toy vehicle inserted into the ball and a switch that turns off power when the vehicle is inverted.
The balls discussed above include complicated transmissions and are not capable of tracking a target. The balls also require initiation and supervision by an operator and are operable only with a limited type of power supply, such as conventional batteries.
This invention provides a tracking device that is movable with six degrees of freedom by controlling movement with one degree of freedom.
In various exemplary embodiments of the tracking device according to this invention, the tracking device includes an external member and an internal member that is rotatable relative to the external member. A motor is attached to the internal member and includes a rotor shaft that is attached to the external member. At least one power source is provided for the motor. A pair of ground contact sensors and a pair of target sensors provide input to a controller so as to increase or decrease the rotation of the internal member with respect to the external member.
These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.